The invention relates to an expansion joint system incorporating damping means, which may be utilized in various roadway constructions where gaps are present between adjacent concrete sections of the roadway construction. The expansion joint including damping means is useful in roadway constructions, including, for example, bridge constructions and other roadway structures where absorption and dissipation of mechanical vibrations is desired.
In a roadway construction, such as highways and bridges, a gap is intentionally provided between adjacent concrete structures for accommodating dimensional changes within the gap occurring as expansion and contraction due to temperature changes, shortening and creep caused by prestressing of the concrete, seismic disturbances, and deflections and longitudinal forces caused by vehicular traffic. An expansion joint is typically utilized to accommodate these movements in the vicinity of the gap.
Bridge constructions are especially subject to dimensional changes and movement caused by seismic events and vehicular traffic. This raises particular problems, because the movements occurring during such seismic events are not predictable either with respect to the magnitude of the movements or to the direction of the movements. In many instances, bridges have become unusable for significant periods of time, due to the fact that traffic cannot travel across damaged expansion joints.
Damping is the absorption of mechanical energy by a material in contact with the source of that energy. It is desirable that the damping materials be highly effective in converting this mechanical energy into heat energy rather than transmitting it to the surroundings.
The use of viscous dampers as “anti-seismic devices” to dampen vibrations caused by seismic cycling and vehicular traffic in bridge construction is known. Viscous dampers typically provide damping by forcing a piston rod into a housing containing a viscous material, such as an oil. The mechanical vibration energy exerted on the bridge structure is decreased when the piston rod pushes through the viscous fluid, as the mechanical energy is converted to heat energy. Thus, damping is achieved. These viscous dampers are often installed across an expansion joint, but are not incorporated into the expansion joint system itself.
Heretofore, the art has not disclosed an expansion joint system having damping means incorporated therein. Therefore, a need still exists for an improved expansion joint system that can absorb and dissipate vibration energy that may be caused by seismic events and vehicular traffic, occurring in the vicinity of a gap having an expansion joint installed between two spaced apart, adjacent roadway sections.